Here's my theory, Cecil was told that her previous lover wanted nothing to do with her anymore by his fiance, but what if the same thing was told to him. That's why he said "water under the bridge..." It's all a big misunderstanding, and that's why they were both reincarnated 500 years later, maybe to have another chance to love each other again, because they were prevented to do so?
Asakura Must Go Downnn ヽ(`Д´)ノ